Variable displacement compressors having a swash ring are well known in the art. Such compressors typically include a plurality of pistons that are driven by the swash ring. The swash ring is operatively coupled to a drive shaft and rotor assembly. The swash ring is angled or inclined relative to the rotor to change the total displacement of the compressor. One well known design includes a pivot pin that is fixed at one end to the drive shaft and pivotally connected to the swash ring at the other end.
Conventional swash ring compressors rely on a sphere to contact the inside of the swash ring supporting the load. Although this design works when the swash ring is made from a hard material, a swash ring made from soft alloys is preferred for improved seizure resistance. To allow a swash ring compressor to use a soft alloy for the swash ring, the load must be distributed over a larger area, which reduces the contact pressure.
While this design achieves its intended purpose many problems still exist. For example, because the pivot pin is located in the drive shaft, the drive shaft must be thicker or larger in diameter resulting in a higher design cost. Moreover, since the swash ring is limited by the pin thickness the compressor will have a large diameter but a poor volumetric efficiency. Further, prior art designs are unable to maintain a constant TDC without holding extremely tight positional tolerances. Further, inserting the pivot pin into the drive shaft at an angle requires expensive gauging. Since a single pivot pin carries the entire load, the pivot pin needs to be made of very expensive heat treated special steels. In addition, designs that include a single pin at a specified angle are not bidirectional thus, clockwise and anticlockwise models must be produced. This of course adds cost and manufacturing complexity. The design further has no provision for a counterweight balancing mass and lacks room for packaging such a mass to offset the pivot pin structure.
For these reasons and others a new and improved swash ring compressor is needed. Such a compressor is herein described below.